Power-driven screwdriver



C. A. HERMAN.

POWER DRIVEN SCREWDRIVER.

APPLICATION FILED ocT. I. I9I9.

Patented Oct. 18, 1921.

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PGWER DRIVENSCREWDRIVER. APPLxcATloN FILED ocT.,1.19'19.

1,394,089. Patented oct. 18, 1921.

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:POWER-DRIVEN SCREWDRIVER.

Specification of' Letters Patent.

Patented Oct. 18, 1921.

Application led October 1, 1919. Serial No. 327,782.

To all whom z't may concern.'

Be it known that I, CLAUDE A. HERMAN, a citizen of the United States, and resident of Bridge ort in the county of F airfield and State of newv and' useful Improvements in Power- Driven Screwdrivers, of which the followin is a specification.

@his invention relates to new and useful improvements in portable power-driven friction screw drivers, such as are used for driving screws, after being positioned, and whereb the screws are permitted to auto matical y stop rotating as soon as they are driven home.

The urpose of the invention is to provide a simp e, compact and reliable form of instrument ofthe above class which may be. connected to be driven with. a flexible shaft and used within the radius of the length of the shaft, for driving screws into machines or parts thereof, and so that. the screw can be'tightly driven home without damaging the screw or parts in which it is driven. Furtherto so construct the device that the rotation of the screw will automatically stop under excessive resistance such for instance as when the head is set against the face of the object in which the screw is driven.

With these and other objects in view the invention resides and consists in the construction and novel combination and ar rangement of parts hereinafter more fully described, illustrated inthe accompanying drawings, and pointed .out in the claims hereto 'a pended, it being understood that various changes in the form, proportion, size and minor details of construction within the scope of the claims may be resorted t o without departure from the spirit or sacri icing any of the advantages of the invention.

Similar characters of reference denote like or corresponding parts throughout the several figures of the accompanying drawings formin a part of this specification, and

. upon w ich,

Figure 1 shows a central'longitudinal section through my improved form of screw driver complete.

Fig. 2 is alongitudinal sectional elevation of the saine showing the screw driver in its normal or inoperative position.

Fig. 3 is a cross section taken on line 3--3 of Fig. 2.

4 is a detached end view ofthe innerv onnecticut, have invented certainv end portion of the driven spindle and the washer mounted thereon.

Fig. 5 shows a detached inner end view of the hand piece, the driving spindle and split friction bushing mounted therein.

Fig. 6 shows a longitudinal view of a modified form of screw driver having an integral handle for turning the tool in the final tightening of a screw, and

Fig. 7 shows a cross section taken on line 7 7 of Fig. 6, to further illustrate the 'purpose of thehandle and ratchet mechanism.

Referring in detail to the characters of reference marked upon the drawings, 6 represents a cylindrical hand piece which preferably has a reduced upper end portion in which a sleeve 7 is threadably attached. A recess 8 is foi-med in the sleeve to receive the iiexible shaft 1 0 and its casing 9. The detachable end of this shaft is in the form vof a plug 11 that is shoved through the sleeve and positioned in the socket 12 and has one side cut away to engage a pin 13 in the spindle 14.. The two end bearing portions of this spindle are journaled and rotate in the cylindrical hand piece 6 and are adapted to y.be continuously operated through the flexible shaft connected thereto. The lower end portion 15 of this spindle is provided with a cylindrical pocket 16 to receive the split friction bushing 17 and whose outer peripheral surfaces are shaped to snugly fit the inner walls of the pocket 16 and whose inner walls are conicalgshaped to receive the corresponding] shaped end 18 of the driven spindle 19. Tp is end portion of the shank isprovided with a key 20 that extends cross- Wise and projects from the opposite sides to engage the ockets 21 formed between the adjacent wall so as to form an operative connection between the friction bushings and the 4shank in addition to the frictional engagement of the tapered end of the shank and the conical walls of the bushing when the shank of the spindle is pressed up into the bushing.

A threaded closure cap 22 is screwed in the lower end of the handle portion and is locked in said position b a set screw 23. This closure cap inclu es a cylindrical chamber of a lesser diameter than that of the hand piece and the inner end of the cap may form an annular shoulder 24 against which the washer 25 is positioned, the opposite side of the washer being similarly engaged by the annular shoulder in the s of the two friction members Y 

